Acoustic diaphragm



93L- H. TENNES SE ET AL I 1,325,833

ACOUSTIC DIAPHRAGM I Filed June 21, 1929 2 sheets -sheet 1 M W/VWWW? Inventor 1%: EN/VEJJE. IR Ease/641 233 Attorney 3 H. TENNESSE ET AL 1,325,833

ACOUSTIC DIAPHRAGM Filed June 21, 1929 2 Sheets-Sheet P I A fimm.

A iiorny Patented Oct. 6, 1931 UNITED STATES PATENT OFFICE HANS TENNESSE AND FREDERICK BASSE, OF NEW YORK, N. Y.

ACOUSTIC DIAPHRAGM Application filed June 21, 1929. Serial No. 372,759.

This invention relates to an improved acoustic diaphragm susceptible of general utility in the art of sound recording and reproduction and has reference in particular to a sound wave responsive element of this class which is expressly useful in radio broadcasting and receiving.

Briefly and generally stated, the invention has reference 11013, vibratory disc of appro- 1Q priate material preferably vulcanized fibre which is constructed to include a plurality of distinct areas which are separately and simultaneously responsive to limited ranges of vibration, the complete area of said disc being sufficientto accommodate all classes of vibrations extending throughout the entire "compass of sound wave vibration produced either vocal, instrumental, mechanical, electrical or otherwise.

More specifically stated, we have evolved and produced a simple and economical vibratory disc which is characterized by a series of eccentric annular bands or areas each of which is a selective vibratory nature to correspond with the vibrations occurring w thin a givenrange of the complete field of vibration, the adjacent bands merging into each other being graduated in thickness from the center throughout the periphery in order to care for an unusually wide range of frequencies and in order to insure of faithful recordation and reproduction of sound waves from the lowermost note of the scale to the highest note or sound of the scale.

In carrying the invention into effect we have found it practicable to provide for an eccentric connection of the vibration bar, electric magnet or other vibratory transmission means utilized in association with the diaphragm.

Other special features of the invention will become more readily apparent from the following description and drawings.

In the drawings Figure 1. is a top plan View of the diaphragm constructed in accordance with the present invention.

Figure 2 is a cross-sectional view taken approximately upon the plane of the. line 22 of Figure 1.

Figure 3 is an unusually large exaggerated view of a fragmentary and sectional nature to bring out the graduated formation of the variegated thicknesses in the construction of the disc.

Figure 4 is a likewise exaggerated fragmentary section taken approximately upon the plane of the line 44 of Figure 1.

The gist of the invention consists in the provision of a diaphragm in the nature of a disc of appropriate vibratory material preferably a vulcanized fibre. In accordance with our conception, however, we provide a disc which is of stepped construction or configuration as shown in Figure 2. \Veaving outwardly from the eccentric point of connection 5 are the diversified annular bands or areas. For sake of convenience and understanding the bands are numbered consecutively as follows. The innermost area is at 6, the next one 7, the next one at 8 and the remaining ones as 9, 10, 11, 12 and 13, respectively. The outermost band 13 is surrounded by a relatively thick attaching rim 14 which defines a shoulder at the juncture 15. Theoretically, this shoulder is presumed to break the outward spiralling and spreading action of the sound waves. Then too, between the points 5 and 15 is the principle vibratory area or field which is supposed to care for the entire compass'of the scale. Thus the shoulder 15 defines the outer limit of vibration and defines within the principle and confined multiple unit field of vibration.

- All of the bands (6 to 13 inclusive) are of the same general configuration in top plan as well as in cross-sectional shape. We can take for example the band 9. Here it will be observed that approximately one-half of the band on the side 16 is comparatively wide whereas on the opposite diametric side 17 it is narrow. The distinction here is that at the point 16 the material in thickness gradually increases around toward the point 17. In other words the point 17 is less responsive than is the point 16. Thus each band in itself cares for an unusual range of vibration. It is, of course, impossible to define the limits of vibration of each band. but these have been worked out from experimentation so Another pointto be noted in connection with the construction is that the various areas 6, 7 and 8, etc. mechanically merge into each other as at 18 in Figure 4 and this occurs on the narrow side of the band. Take for example, the band 9, this merges at the point 17 into the corresponding thin and narrow point of the next adjacent band 10 and so on.

It is, of course, understood that the thicker and smaller areas LOJVard the center serve to accommodate high frequencies for soprano voice, violin, flute and other instruments of analogous intensity and high rate vibration. The wider and outer band accommodates the intermediate and lower tones.

From the foregoing description and drawings it will be seen that we have evolved and produced a new type and species of vibrator v diaphragm intended for general industrial purposes but specifically adaptable for use in sound recording and reproducing machines such as phonographs, radios and the like. The properties of the diaphragm are such as to insure uniform activity, selective vibration, natural and unusual sensitivity and faithful and true responsiveness whereby to avoid irritating distortion. This is based on the principle of utilization of succeeding annular bands of a tapered nature merging into each other from the center outwardly and terminating in an upstanding peripheral rim. in order to define the selective areas which may simultaneously or separately vibrate according to the nature of sounds.

It is thought that persons skilled in the art to which the invention relates will be .able to obtain a clear understanding of the same after considering the detail description in connection with the drawings. Therefore, a more lengthy description is believed to be unnecessary.

Minor changes in shape, size, materials and re-arrangement of features coming within the field of invention claimed may be resorted to in actual practice if desired.

We claim 1. An acoustic diaphragm, comprising a main body portion formed to provide a plurality of circumferentially extending vibrating areas, each increasing in width and decreasing in thickness from a minimum dimension to a maximum dimension.

2. An acoustic diaphragm, comprising a main body portion formed to provide a plurality of eccentrically arranged circumferenti ally extending vibrating areas, each varying in thickness from a minimum thickness at one point in its circumference to a maximum thickness at a diametrically opposed point.

3. An acoustic diaphragm, comprising a main body portion formed to provide a plurality of relatively narrow circumferentially extending vibrating areas, each having a point of minimum thickness and increasing in thickness in opposite directions from one point in its circumference to a diametrically opposite point of maximum thickness.

4. An acoustic diaphragm comprising a main body portion formed to provide a plurality of relatively narrow circumferentially extending vibrating areas, each area being of a different thickness than the next adjacent area, and of different thickness at different points in its own circumference.

In testimony whereof we afiix our signatures.

HANS TENNESSE. FREDERICK BASSE. 

